1. Field of the Invention
The present invention relates generally to a portable electronic device having a built-in geomagnetic sensor. More particularly, the present invention relates to a portable electronic device of determining a rotation state by means of a geomagnetic sensor and rotating a menu to be displayed on a screen based on the determination, and a method for the same.
2. Description of the Related Art
As electronic technologies have been developed, various portable electronic devices such as a cellular phone, a Personal Digital Assistant (PDA), a notebook, a Personal Computer (PC) or the like have been developed and have become popular. In particular, companies that manufacture such portable electronic devices are inciting users to buy products by adding various and handy functions to the portable electronic devices in recent years. By way of example, a camera function is added to the cellular phone to allow a simple picture or a moving picture to be picked up, or an acceleration sensor or a gyro sensor is built in the portable electronic device to allow a current inclination state or a rotational angular velocity or the like to be measured so that users may obtain various information. The acceleration sensor serves to use a signal corresponding to a change of acceleration of gravity to thereby obtain positional information, and the gyro sensor serves to measure a Coriolis force to detect the rotational angular velocity.
FIGS. 1A and 1B are schematic diagrams of a camera phone 10 which has rapidly become popular in recent years as an example of portable electronic devices. Users check the images displayed on a Liquid Crystal Display (LCD) 11 of the camera phone 10, and adjust various buttons 12 to carry out the pickup.
The users may carry out the pickup not in a typical longitudinal direction but in a horizontal direction. In other words, the users may usually carry out the pickup in the longitudinal direction as shown in FIG. 1A, however, the users may carry out the pickup in the horizontal direction by rotating the camera phone 10 by 90° as shown in FIG. 1B. In this case, the image which is incident through a lens to be displayed on the LCD 11 is maintained as it is, however, an On Screen Display (OSD) menu 11b such as “pickup”, “send” or a current mode display 11a of the camera phone such as “take a picture” which are to be displayed on the screen of the camera phone 10 is rotated along with the camera phone 10. As a result, these menu displays are represented in the longitudinal direction, which causes the users to feel inconvenience.
As an alternative, the acceleration sensor or the gyro sensor may be built in the cellular phone to allow the menu being displayed on the screen after measurement of the rotation state to be rotated, however, the acceleration sensor relatively consumes a large amount of power and has less durability against impact, and the gyro sensor also has lees durability against impact and costs too much. Also, both the accelerator sensor and the gyro sensor are difficult to manufacture small enough to be employed in the portable electronic device.